Wall decoration material is an important part of the construction of buildings and an important area of development in new building materials. Construction is a pillar industry of national economy and also a fundamental work of construction modernization. At present, annual completed urban dwelling building area is about 335 million m2, annual completed village and town dwelling building area is about 500 million m2, and annual completed public buildings and production buildings in cities, towns, and villages is about 600 million m2. Calculated at 2.5 times of total completed building area, the area of required wall decoration material is about 4.0 billion m2. The huge market demand lays a good foundation for development of new wall decoration materials.
At present, there are many types of traditional indoor wall decoration materials. In domestic and overseas markets, these mainly include: gypsum board, aluminum plastic board, polyester fiber board, mineral wool board, new type fiber cement board used for external walls, environment friendly carpentry board, and plywood. However, not many of the products in the market fully meet the standard for environment friendly building materials. To a large extent, there is no decoration product made of regenerated material, hence being totally environment friendly. Plastic products are subject to hardening and embrittlement, and discoloring after being used for a long period of time. In addition, after being scrapped, degradation is a very difficult issue and may cause serious environment pollution. Although gypsum products are inexpensive and have a natural appearance, they are not elegant enough and subject to moisturing, falling, and discoloring (becoming yellow). Wood chip products are mostly used as inner lining of furniture decoration boards, and attached with decoration pattern veneer on the exterior. They are subject to problems of low firmness and can cause pollutions due to the adhesive used. The commonly used medium density fiberboard has good appearance and internal quality, but includes the adhesive that pollutes indoor environment and is expensive and requires more raw materials. This material is mainly used as a high grade decoration material.
Materials such as plywood and timber used for decoration and partition at present are basically inflammable materials. Although flame-resisting materials can be seen on the market, those materials are normally difficult to make and are very heavy. For example, the gypsum board has a high ignition point, and when burnt or subject to dry and hot weather, gypsum is prone to embrittlement, even bending, peeling, and cracking. In particular, in the situation of aggravated global greenhouse effect and the rise of air temperature year after year, as a flame-resisting material, gypsum cannot meet requirements on modern indoor decoration and improvement is urgently needed.
At present, most decoration boards in the market adopt a dry process, e.g. gypsum board, artificial decoration face board, polyester fiberboard, mineral wool board, plywood, etc. Most plant fiber wall panels adopt a dry process, i.e. mix crushed materials (corn stalk, straw, wheat stalk, bran coat, saw dust, etc.) with starch gum or thermo-plastic polymer, coupling agent, blowing agent, and lubricant etc. under normal temperature, and manually or mechanically feed the material to the mold, where pressing, squeezing, and forming is carried out. Steps of the dry process include crushing raw materials, adding additives and mixing them, loading, hot pressing, and forming, mold unloading, and obtaining the finished product. The disadvantages are: 1. A true environment friendly product capable of total degradation cannot be made. Most products in the market made by this process contain additions of some photolytic material or a small amount of starch not capable of degradation so as to be decomposed into fine powder. This is not a true degradation, and hence environmental pollution and its hazards remain. 2. Some products with starch added are subject to mold rotting in a wet environment and cannot last long. 3. They are very heavy, causing a relatively higher transport cost, and resulting in heavier wastes to be treated.
Among the technologies that have been disclosed at the present time, Chinese Patent CN1108988A discloses “A hardboard production process using dry and glue-free method”, a method that subjects plant raw materials to fiber separation and drying, followed by forming and hot pressing without using synthetic resin, to yield a type of artificial board. Products made by this method have relatively low strength.
Chinese Patent CN1654180 discloses “An enclosed hot pressing process to make glue-free fiberboard”, which provides a method to manufacture glue-free fiberboard of a low hot pressing pressure and relatively large range of product thickness and density. Due to the raw materials and specific process used, this type of fiberboard has an insufficient strength when the thickness is relatively small.
Chinese Patent CN1184161C discloses “A flame-resistant environment friendly decoration board and its method of manufacture”, which provides a type of formaldehyde-free, flame-resistant, easy-to-make, low cost and environment friendly decoration board and its manufacture process. However, this dry process utilizes a conventional flame retardant and then sticky rice paste as adhesive for pressing and forming, so that the process is relatively complicated and is not a wet method.
Existing fiberboard products made by a wet forming process are mainly those having a thickness less than 5 mm, e.g. tableware. Such process basically adopts steam pressure type driving and pressing step, with a relatively low pressing pressure, so that a product exceeding certain thickness cannot be made and the surface precision is relatively low, let alone forming a convex-concave pattern. Up to now, there is no report that the paper pulp molding solid wet method of the paper making technology is used to manufacture flame-resisting fiber wall panels.